(a) Field of the Invention
The present invention relates to liquid crystal displays (LCDs) and a manufacturing method thereof, in particular, to vertically-aligned liquid crystal displays (VA LCDs) having multi-domains in a pixel region and a manufacturing method thereof.
(b) Description of the Related Art
A liquid crystal display (LCD) includes two substrates and a liquid crystal layer interposed therebetween. The transmittance of the incident light is controlled by the strength of the electric field applied to the liquid crystal layer.
A vertically aligned twisted nematic (VATN) liquid crystal display has a couple of transparent substrates which have transparent electrodes respectively on their inner surfaces, a chiral nematic liquid crystal layer having negative anisotropy between the substrates and a couple of polarizers which are respectively attached to the outer surfaces of the substrates In the off state of the LCD, i.e., in the state that the electric field is not applied to the liquid crystal layer, the molecular axes or the long axes of the liquid crystal molecules are perpendicular to the substrates. On the other hand, in the on state of the LCD, i.e., in the state that the sufficient electric field caused by the voltage difference between the electrodes is applied to the liquid crystal layer, the long axes of the liquid crystal molecules are parallel to the substrates by the negative anisotropy and twisted spirally by the chirality with a pitch from the inner surface of one substrate to that of the other substrate. Accordingly, the orientation of the long axes of the liquid crystal molecules vary continuously.
A VATN LCD in normally black mode may have an off state which is sufficiently dark because the molecular axes of the liquid crystal molecules are uniformly aligned perpendicular to the substrates in the off state. Therefore, the contrast ratio is relatively high compared with a conventional TN LCD. In addition, the viewing angle may be strongly dependent on the viewing directions. Therefore, it is suggested to form multi-domains in a pixel by providing apertures in the electrode by Clere in U.S. Pat. No. 5,136,407 and by Hirose in U.S. Pat. No. 5,229,873, etc.